Computer tomography image reconstruction

ABSTRACT

A method for reconstructing a Computer Tomography (CT) image is disclosed. The method may comprise: obtaining a X-ray projection data frame and a dynamic sensor information data frame, wherein the X-ray projection data frame may include a first timestamp indicating acquisition time of X-ray projection data and the dynamic sensor information data frame may include a second timestamp indicating acquisition time of dynamic sensor information data; extracting the first timestamp from the X-ray projection data frame and extracting the second timestamp from the dynamic sensor information data frame; searching X-ray projection data and dynamic sensor information data which may be acquired in same sampling period according to a first timestamp and a second timestamp; and reconstructing a CT image according to the searched X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Chinese Patent ApplicationNo. 201410817435.5, filed on Dec. 24, 2014, the entire contents of whichare hereby incorporated by reference for all purposes.

BACKGROUND

The present invention relates to the technical field of medical imagingand, more particularly, to a Computer Tomography (CT) imagereconstruction.

NEUSOFT MEDICAL SYSTEMS CO., LTD. (NMS), founded in 1998 with its worldheadquarters in China, is a leading supplier of medical equipment,medical IT solutions, and healthcare services. NMS supplies medicalequipment with a wide portfolio, including CT, MRI, digital X-raymachines, Ultrasound, PET (Positron Emission Tomography), LinearAccelerators, and Biochemistry Analysers. Currently, NMS' products areexported to over 60 countries and regions around the globe, serving morethan 5,000 renowned customers. NMS' latest successful developments, suchas the 128 Multi-Slice CT Scanner System, Superconducting MRI, LinearAccelerator, and PET products, have led China to become a globalhigh-end medical equipment producer. As an integrated supplier withextensive experience in large medical equipment, NMS is committed to thestudy of avoiding secondary potential harm caused by excessive X-rayirradiation to the subject during the CT scanning process.

BRIEF DESCRIPTION OF DRAWINGS

Features of the present disclosure are illustrated by way of example andnot limited in the following figure(s), in which like numerals indicatelike elements, in which:

FIG. 1A is a schematic diagram of an architecture of a CT scanningsystem, according to an example of the present disclosure;

FIG. 1B is a flowchart of a method for CT image reconstruction,according to an example of the present disclosure;

FIG. 2 is a schematic diagram of a sampling signal and inserting time ofa first timestamp, according to an example of the present disclosure;

FIG. 3 is a schematic diagram of a CT scanning system receiving acardiac cycle Electrocardiography (ECG) signal from an ECG monitoringdevice, according to an example of the present disclosure;

FIG. 4 is a flowchart of a method for cardiac CT image reconstruction,according to an example of the present disclosure;

FIG. 5 is a schematic diagram of a hardware structure of an apparatusfor CT image reconstruction, according to an example of the presentdisclosure; and

FIG. 6 is a schematic diagram of function modules of control logic forreconstructing a CT image, according to an example of the presentdisclosure.

DETAILED DESCRIPTION

For simplicity and illustrative purposes, the present disclosure isdescribed herein by referring mainly to an example thereof. In thefollowing description, numerous specific details are set forth in orderto provide a thorough understanding of the present disclosure. It willbe readily apparent however, that the present disclosure may bepracticed without limitation to these specific details. In otherinstances, some methods and structures may not be described in detail soas not to unnecessarily obscure the present disclosure. As used herein,the terms “a” and “an” are intended to denote at least one of aparticular element, the term “includes” means includes but not limitedto, the term “including” means including but not limited to, and theterm “based on” means based at least in part on.

In a typical CT scanning system, a data acquisition unit at a rotationend of the system may periodically acquire X-ray projection dataaccording to a sampling period signal, wherein the rotation end may be arotatable gantry device. The data acquisition unit may generate an X-rayprojection data frame according to acquired X-ray projection data in onesampling period. At the same time, a sensor acquisition unit may acquiredynamic sensor information and transmit said dynamic sensor informationto a data acquisition unit, wherein a dynamic sensor information may bethe horizontal position of bed, ECG, etc. The data acquisition unit mayinsert the dynamic sensor information into the X-ray projection dataframe according to a pre-defined frame format of an X-ray projectiondata frame. Then, the data acquisition unit may transmit the X-rayprojection data frame with the dynamic sensor information to an imagereconstruction unit at a stationary end through a data transmission slipring. Finally, the image reconstruction unit may reconstruct a CT imageaccording to an X-ray projection data frame with the dynamic sensorinformation.

In order to reconstruct a high quality CT image, the dynamic sensorinformation which may be acquired at the same sampling period with theX-ray projection data, may be transmitted to the data acquisition unitin the same sampling period. Therefore, it may be very important tocontrol the transmission delay of the dynamic sensor information,especially for a dynamic sensor information with a large transmissiondelay. The dynamic sensor information with a large transmission delaymay comprise the horizontal movement information of the scan bed.

In addition, the dynamic sensor information may usually be transmittedalong with other information commands, such as a query command of therotary end state, a response command of the data acquisition command,etc. The dynamic sensor may use the command transmission slip ring inorder to transmit the dynamic sensor information and other informationcommands in multiplex. In general, a command transmission slip ring maybe a brush contact structure. Thus, the signal transmission efficiencyof the command transmission slip ring may not be too high, and thetransmission delay of the command transmission slip ring may be verylarge. In addition, in order to ensure the command signal be transmittedin real-time, the priority of the command signal may be higher than thatof the dynamic sensor information. Thus, the transmission delay of thedynamic sensor information may be increased. Additionally, thecommunication protocol of the command signal may have a response andretransmission mechanisms, particularly during the CT scanning period.When the command transmission slip ring may be affected byelectromagnetic interference or mechanical vibration, it may causecommand signal retransmitting and further increase the transmissiondelay of dynamic sensor information. Thus, the transmission delay of thedynamic sensor information may be unpredictable.

The transmission delay of the dynamic sensor information may be largeand unpredictable as discussed briefly above. Such a delay may cause thedynamic sensor information to not be transmitted to the data acquisitionunit in one sampling period. Additionally, the correspondence betweenthe X-ray projection data frame and the dynamic sensor informationacquired in the same sampling period may be deviated, thereby affectingthe quality of the reconstructed CT image.

FIG. 1A is a schematic diagram of an architecture of a CT scanningsystem according to an example of the present disclosure. FIG. 1B is aflowchart of a method for CT image reconstruction according to anexample of the present disclosure. The descriptions of blocks of FIG. 1Bmay be referenced with the components of FIG. 1A.

As shown in FIG. 1B, at block S11, the image reconstruction unit 140 mayobtain an X-ray projection data frame and a dynamic sensor informationdata frame.

In this example, the X-ray projection data frame may include a firsttimestamp indicating acquisition time of the X-ray projection data, andthe dynamic sensor information data frame may include a second timestampindicating acquisition time of the dynamic sensor information data.Thus, the image reconstruction unit 140 may retrieve the X-rayprojection data and the corresponding dynamic sensor information dataaccording to a first timestamp of the X-ray projection data frame and asecond timestamp of the dynamic sensor information data frame.Therefore, it may ensure the quality of the reconstruction image.

An X-ray projection data frame may include X-ray projection dataacquired in one sampling period. A dynamic sensor information data framemay include dynamic sensor information data acquired in onepre-determined time period. In general, the pre-determined time periodmay not be greater than the sampling period. For example, thepre-determined time period may be less than or equal to the samplingperiod. Thus, in one sampling period, it may be possible to generate atleast one dynamic sensor information data frame. For example, when thepre-determined time period may be much less than the sampling period, itmay generate a plurality of dynamic sensor information data frames inone sampling period.

In addition, the length of the sampling period may usually be associatedwith the rotational speed of a rotatable gantry of the CT scanningsystem. For example, the higher the rotational speed may be, the shorterthe sampling period may be.

According to an example, at block S11, obtaining the X-ray projectiondata frame may further comprise block S11 a 1 (not shown in FIG. 1B) andblock S11 a 2 (not shown in FIG. 1B).

At block S11 a 1, the X-ray projection data frame may acquire X-rayprojection data according to a sampling period signal and recordacquisition time of the X-ray projection data.

Specifically, the data acquisition unit 110 at the rotation end mayacquire X-ray projection data according to the sampling period signaland record acquisition time of the X-ray projection data.

According to one example, the X-ray projection data frame may recordacquisition time of the X-ray projection data by a first counter 111. Asshown in FIG. 1A, the first counter 111 may be provided in the dataacquisition unit 110. The value of the first counter 111 may beincremented by 1 in each fixed time period. Thus, the count value of thefirst counter 111 may represent time. In general, the fixed time periodmay be less than the sampling period.

Further, when the data acquisition unit 110 receives a start scanninginstruction from the main control unit 150, a first counter 111 may beactivated. When the data acquisition unit 110 receives an end scanninginstruction from the main control unit 150, the first counter 111 may bereset and turned off. As shown in FIG. 1A, scan instructions from themain control unit 150 may be transmitted to the data acquisition unit110 via a slip ring 160, wherein the scan instructions may comprise thestart scanning instruction and the end scanning instruction.

Further, it may latch up the value of a first counter 111 based on arising edge of the sampling period signal. The latched value of thefirst counter 111 may be used to indicate an acquisition time of theX-ray projection data. FIG. 2 is a schematic diagram of a samplingperiod signal and an inserting time of a first timestamp according to anexample of the present disclosure

At block S11 a 2, the data acquisition unit may generate an X-rayprojection data frame according to X-ray projection data acquired in thesame sampling period and corresponding acquisition time, wherein theacquisition time may be recorded into a timestamp field of the X-rayprojection data frame as the first timestamp.

In general, the X-ray projection data frame may have a pre-defined frameformat in which deploys a timestamp field. The data acquisition unit mayrecord the acquisition time of the X-ray projection data into thetimestamp field of the X-ray projection data frame as a first timestamp.At the same time, the data acquisition unit may generate an X-rayprojection data frame according to the X-ray projection data which maybe acquired in the same sampling period. Thus, the generated X-rayprojection data frame may comprise X-ray projection data and acquisitiontime of the X-ray projection data.

Thereafter, the data acquisition unit 110 may transmit the generatedX-ray projection data frame through a slip ring 130 to the imagereconstruction unit 140.

According to an example, at block S11, obtaining the dynamic sensorinformation data frame may comprise block S11 b 1 (not shown in FIG. 1B)and block S11 b 2 (not shown in FIG. 1B).

At block S11 b 1, the data acquisition unit may acquire dynamic sensorinformation data and record acquisition time of the dynamic sensorinformation data.

Specifically, the sensor acquisition unit 120 may acquire dynamic sensorinformation data and record acquisition time of the dynamic sensorinformation data, wherein the dynamic sensor information data may beacquired by a dynamic monitoring equipment (not shown in FIG. 1A). Forexample, according to scan protocol settings of a CT scanning system,the sensor acquisition unit 120 may receive real-time dynamic sensorinformation data acquired by dynamic monitoring equipment. The sensoracquisition unit 120 may record receipt time of received dynamic sensorinformation data as the acquisition time of the received dynamic sensorinformation data.

Furthermore, in the CT scanning system of the present disclosure, thedata amount of the dynamic sensor information data may be substantiallyless than that of the X-ray projection data. Thus, a relatively highfrequency for acquiring the dynamic sensor information data may presentadvantages in subsequent processing in order to search X-ray projectiondata and dynamic sensor information data which may be acquired in thesame sampling period.

According to one example, sensor acquisition unit 120 may recordacquisition time of the dynamic sensor information data by a secondcounter 121. As shown in FIG. 1A, the second counter 121 may be providedin the sensor acquisition unit 120. The value of a second counter 121may be incremented by 1 in a fixed time period. Thus, the count value ofthe second counter 121 may represent time. In general, the fixed timeperiod may be less than the sampling period.

Further, when the sensor acquisition unit 120 receives a start scanninginstruction from the main control unit 150, the second counter 121 maybe activated. When the sensor acquisition unit 120 receives an endscanning instruction from the main control unit 150, the second counter121 may be reset and subsequently turned off. As shown in FIG. 1A, scaninstructions from the main control unit 150 may be directly transmittedto the sensor acquisition unit 120, wherein the scan instructions maycomprise a start scanning instruction and an end scanning instruction.

At block S11 b 2, the sensor acquisition unit may generate a dynamicsensor information data frame according to dynamic sensor informationdata acquired in the same pre-determined time period and correspondingacquisition time, wherein the acquisition time may be recorded into atimestamp field of the dynamic sensor information data frame as a secondtimestamp.

In general, the dynamic sensor information data frame may also comprisea pre-defined frame format in which deploys a timestamp field. Thesensor acquisition unit may record the acquisition time of the dynamicsensor information data into a timestamp field of the dynamic sensorinformation data frame as a second timestamp. At the same time, thesensor acquisition unit may generate a dynamic sensor information dataframe according to the dynamic sensor information data which may beacquired in the same pre-determined time period. Thus, the generateddynamic sensor information data frame may comprise the dynamic sensorinformation data and the acquisition time of the dynamic sensorinformation data.

In addition, according to the aforementioned descriptions, apre-determined time period may usually not be greater than one samplingperiod. Thus, in one sampling period, the sensor acquisition unit mayacquire at least one set of dynamic sensor information data. Therefore,it may generate at least one dynamic sensor information data frame inone sampling period.

Thereafter, the sensor acquisition unit 120 may transmit a generateddynamic sensor information data frame to an image reconstruction unit140.

At block S12, the image reconstruction unit may extract a firsttimestamp from the X-ray projection data frame and extract a secondtimestamp from a dynamic sensor information data frame.

For example, the image reconstruction unit 140 may extract a firsttimestamp from the X-ray projection data frame according to the frameformat of the X-ray projection data frame, and extract a secondtimestamp from the dynamic sensor information data frame according tothe frame format of the dynamic sensor information data frame.

At block S13, the image reconstruction unit may search X-ray projectiondata and dynamic sensor information data which may be acquired in thesame sampling period according to a first timestamp and a secondtimestamp.

According to a first timestamp and a second timestamp, the sensoracquisition unit may decide the acquisition time of the X-ray projectiondata and the acquisition time of the dynamic sensor information data,respectively. An image reconstruction unit 140 may search X-rayprojection data and dynamic sensor information data which may beacquired in the same sampling period according to a timestamp and asecond timestamp.

For example, the sensor acquisition unit may use a first counter 111 anda second counter 121 to record the acquisition time of the X-rayprojection data and the acquisition time of the dynamic sensorinformation data, respectively. The first counter 111 and the secondcounter 121 may be activated when receiving a start scanninginstruction. Since the delays of scan instructions being transmitted tothe first counter 111 and the second counter 121 may both be fixed, thesensor acquisition unit may previously calculate the difference betweenthe delay of the scan instruction being transmitted to a first counter111 and the delay of the scan instruction being transmitted to a secondcounter 121 as a compensation amount. Then, the sensor acquisition unitmay use the compensation amount to calibrate an offset between theacquisition time of the X-ray projection data recorded by a firstcounter 111 and the acquisition time of the dynamic sensor informationdata recorded by a second counter 121. The image reconstruction unit 140may search X-ray projection data and dynamic sensor information datawhich may be acquired in same sampling period in accurate.

In block S14, the image reconstruction unit 140 may reconstruct a CTimage according to the searched X-ray projection data and dynamic sensorinformation data which may be acquired in the same sampling period.

In the process of reconstructing a CT image, the X-ray projection datamay be dynamically compensated according to the dynamic sensorinformation data which may be acquired in the same sampling period withthe X-ray projection data, so that a reconstructed CT image may be moreclear than before.

The image reconstruction unit 140 may use the timestamps provided inorder to implement an accurate search for X-ray projection data anddynamic sensor information data which may be acquired in the samesampling period, so as to avoid any influence from transmission delay ofthe dynamic sensor information data. Nevertheless, whether the X-rayprojection data is received earlier or later than the dynamic sensorinformation data, the image reconstruction unit may find X-rayprojection data and dynamic sensor information data which may beacquired in the same sampling period, dynamically compensate the X-rayprojection data according to the dynamic sensor information dataacquired in the same sampling period with the X-ray projection data, andthus reconstruct a substantially clearer CT image.

FIG. 3 is a schematic diagram of an example CT scanning system receivinga cardiac cycle ECG signal from an ECG monitoring device and a cardiacCT image reconstruction according to an example of the presentdisclosure. In general, in order to reconstruct a clear cardiac CTimage, it may be beneficial to adopt an X-ray projection data frame ofwhich the acquisition time may correspond to a specific time interval.In the specific time interval, shown as dashed lines in FIG. 3 duringone cardiac cycle period, the heart may have remained in a relativestationary state.

FIG. 4 is a flowchart of a method for cardiac CT image reconstructionaccording to an example of the present disclosure. As shown in FIG. 4,the method may comprise blocks S41 to S48.

At block S41, the data acquisition unit 110 of the CT scanning systemmay acquire X-ray projection data, record acquisition time of the X-rayprojection data, and generate an X-ray projection data frame accordingto the X-ray projection data and corresponding acquisition time, whereinthe acquisition time may be recorded into a timestamp field of the X-rayprojection data frame as a first timestamp.

At block S42, the sensor acquisition unit 120 of the CT scanning systemmay receive a cardiac cycle ECG signal from an ECG monitoring device.

At block S43, the sensor acquisition unit 120 of the CT scanning systemmay generate a dynamic sensor information data frame according to thecardiac cycle ECG signal and other dynamic sensor information data, andinsert a second timestamp and a peak identifier (R) into the dynamicsensor information data frame, wherein a second timestamp may representacquisition time of the cardiac cycle ECG signal and a peak identifier(R) may indicate whether the signal is an ECG signal or not.

According to one example, before generating a dynamic sensor informationdata frame, the sensor acquisition unit may convert a cardiac cycle ECGsignal from an analogue domain to a digital domain, and may generate thedynamic sensor information data frame according to a digital cardiaccycle ECG signal.

At block S44, the image reconstruction unit 140 of the CT scanningsystem may obtain an X-ray projection data frame and a dynamic sensorinformation data frame.

At block S45, when the peak identifier R of an ECG signal in a dynamicsensor information data frame is detected to be valid, the imagereconstruction unit 140 may obtain a first time (T1) from a startscanning time to a peak identifier R as shown in FIG. 3.

At block S46, according to characteristics of an ECG signal and a firsttime T1, the image reconstruction unit may obtain a second time (T2)from a start scanning time to a starting time of a relative stationarystate of the heart in a cardiac cycle period.

At block S47, the image reconstruction unit may search the firsttimestamp which may be nearest to a second time T2 as a starting pointof the acquisition time of the X-ray projection data, thus the X-rayprojection data corresponding to the searched first timestamp may beacquired in a relative stationary state of the heart in a cardiac cycleperiod. By using a first timestamp and a second time stamp, the imagereconstruction unit may select, based on the searched starting point ofthe acquisition time, the X-ray projection data and the dynamic sensorinformation data which may correspond to a relative stationary state ofthe heart in the cardiac cycle period. For example, a relativestationary state of the heart in the cardiac cycle period may be thetime interval shown as the dashed lines in FIG. 3.

At block S48, the image reconstruction unit may use the X-ray projectiondata and the dynamic sensor information data corresponding to a relativestationary state of the heart in the cardiac cycle period in order toreconstruct a cardiac CT image.

The present disclosure also provides an apparatus for CT imagereconstruction. FIG. 5 is a schematic diagram of the hardware structureof the apparatus for CT image reconstruction according to an example ofthe present disclosure. As shown in FIG. 5, an apparatus for CT imagereconstruction may comprise a processor 51, a storage medium 52, aninternal bus 53, and an interface 54. The storage medium 52 and theinterface 54 may be accessible by the processor 51 through an internalbus 53.

The storage medium 52 may be a non-volatile memory or storage mediaincluding, by way of example, semiconductor memory devices, such asEPROM, EEPROM, DRAM and flash memory devices; magnetic disks, e.g.,internal hard disks or removable disks; magneto optical disks; and CDROM and DVD-ROM disks.

Further, the storage medium 52 may store machine readable instructionscorresponding to a control logic 60 for reconstructing CT image. FIG. 6is a schematic diagram of function modules of the control logic 60 forreconstructing CT images according to an example of the presentdisclosure. As shown in FIG. 6, the control logic 60 for reconstructingCT image may comprise an acquisition module 61, an extraction module 62,a search module 63, and a reconstruction module 64.

The acquisition module 61 may obtain the X-ray projection data frame andthe dynamic sensor information data frame, wherein the X-ray projectiondata frame may comprise a first timestamp indicating acquisition time ofX-ray projection data and the dynamic sensor information data framewhich may comprise a second timestamp indicating acquisition time ofdynamic sensor information data. The X-ray projection data comprised inan X-ray projection data frame may be acquired in one sampling period,and the dynamic sensor information data comprised in a dynamic sensorinformation data frame may be acquired in one pre-determined timeperiod, and the pre-determined time period may not be longer in durationthan a sampling period.

The extraction module 62 may extract the first timestamp from an X-rayprojection data frame and extract a second timestamp from a dynamicsensor information data frame.

The search module 63 may search X-ray projection data and dynamic sensorinformation data which may be acquired in the same sampling periodaccording to a first timestamp and a second timestamp.

The reconstruction module 64 may reconstruct a CT image according to thesearched X-ray projection data and dynamic sensor information data whichmay be acquired in the same sampling period.

According to one example, the acquisition module 61 may include a dataacquisition sub-module 611, an X-ray projection data frame generationsub-module 612, a data receiving sub-module 613, and a dynamic sensorinformation data frame generation sub-module 614.

The data acquisition sub-module 611 may be used to acquire X-rayprojection data according to a sampling period signal and recordacquisition time of the X-ray projection data.

The X-ray projection data frame generation sub-module 612 may be used togenerate an X-ray projection data frame according to the X-rayprojection data acquired in the same sampling period and thecorresponding acquisition time, wherein the acquisition time may berecorded into a timestamp field of the X-ray projection data frame as afirst timestamp

Furthermore, the data acquisition sub-module 611 may use a first counterto record the acquisition time of the X-ray projection data, wherein thevalue of the first counter may be incremented by 1 in a fixed timeperiod and the fixed time period may be shorter in duration than thesampling period.

The data receiving sub-module 613 may be used to receive acquireddynamic sensor information data and record acquisition time of thedynamic sensor information data.

The dynamic sensor information data frame generation sub-module 614 maybe used to generate a dynamic sensor information data frame according tothe dynamic sensor information data acquired in a pre-determined timeperiod and the corresponding acquisition time, wherein the acquisitiontime may be recorded into a timestamp field of the dynamic sensorinformation data frame as the second timestamp.

Furthermore, the data receiving sub-module 613 may use a second counterto record the acquisition time of the dynamic sensor information data,wherein the value of a second counter may be incremented by 1 in a fixedtime period and the fixed time period may be shorter in duration thanthe sampling period.

The following technology may be implemented in software which isdescribed the operation of the control logic 60 for reconstructing a CTimage. The control logic 60 for reconstructing a CT image may be themachine readable instructions stored in the storage medium 52. Theprocessor 51 of the apparatus for CT image reconstruction may read theinstructions of corresponding modules of the control logic 60 forreconstructing a CT image stored in the storage medium 52 and mayexecute the instructions.

The instructions executed by the processor 51 may cause the processor 51to perform the following operations.

The processor 51 may obtain an X-ray projection data frame and a dynamicsensor information data frame, wherein the X-ray projection data framemay comprise a first timestamp indicating acquisition time of X-rayprojection data and the dynamic sensor information data frame maycomprise a second timestamp indicating acquisition time of dynamicsensor information data.

The processor 51 may extract a first timestamp from the X-ray projectiondata frame and extract a second timestamp from the dynamic sensorinformation data frame.

The processor 51 may search X-ray projection data and dynamic sensorinformation data which may be acquired in the same sampling periodaccording to a first timestamp and a second timestamp.

The processor 51 may reconstruct a CT image according to the searchedX-ray projection data and dynamic sensor information data which may beacquired in the same sampling period.

The X-ray projection data comprised in a X-ray projection data frame maybe acquired in a sampling period, the dynamic sensor information datacomprised in a dynamic sensor information data frame may be acquired ina pre-determined time period, and the pre-determined time period may beless than or equal to the sampling period.

According one example of present disclosure, when obtaining the X-rayprojection data frame, the instructions executed by the processor 51 maycause the processor 51 to perform the following operations.

The processor 51 may acquire X-ray projection data according to thesampling period signal and may record acquisition time of the X-rayprojection data.

The processor 51 may generate an X-ray projection data frame accordingto X-ray projection data acquired in the same sampling period andcorresponding acquisition time, wherein the acquisition time may berecorded into a timestamp field of the X-ray projection data frame as afirst timestamp.

Furthermore, when recording the acquisition time of the X-ray projectiondata, the instructions executed by the processor 51 may cause theprocessor 51 to perform the following operations. The processor 51 mayuse a first counter to record the acquisition time of the X-rayprojection data, wherein the value of a first counter may be incrementedby 1 in a fixed time period and the fixed time period may be shorter induration than the sampling period.

According one example of present disclosure, for obtaining of thedynamic sensor information data frame, the instructions executed by theprocessor 51 may cause the processor 51 to perform the followingoperations.

The processor 51 may acquire dynamic sensor information data and recordacquisition time of the dynamic sensor information data.

The processor 51 may generate a dynamic sensor information data frameaccording to dynamic sensor information data acquired in the samepre-determined time period and corresponding acquisition time, whereinthe acquisition time may be recorded into a timestamp field of thedynamic sensor information data frame as a second timestamp.

Furthermore, when recording the acquisition time of the dynamic sensorinformation data, the instructions executed by the processor 51 maycause the processor 51 to perform the following operations. Theprocessor 51 may use a second counter to record the acquisition time ofthe dynamic sensor information data, wherein the value of the secondcounter may be incremented by 1 in a fixed time period and the fixedtime period may be shorter in duration than the sampling period.

The above are only preferred examples of the present disclosure and arenot intended to limit the disclosure within its spirit and principles.Any changes made, equivalent replacements, or improvement in theprotection of the present disclosure should be contained within itsrange.

The methods, processes and units described herein may be implemented byhardware (including hardware logic circuitry), software or firmware or acombination thereof. The term ‘processor’ is to be interpreted broadlyto include a processing unit, ASIC, logic unit, or programmable gatearray etc. The processes, methods and functional units may all beperformed by the one or more processors; reference in this disclosure orthe claims to a ‘processor’ should thus be interpreted to mean ‘one ormore processors’.

Further, the processes, methods and functional units described in thisdisclosure may be implemented in the form of a computer softwareproduct. The computer software product may be stored in a storage mediumand may comprise a plurality of instructions for making a processor toimplement the methods recited in the examples of the present disclosure.

The figures are only illustrations of an example, wherein the units orprocedure shown in the figures may not be necessarily essential forimplementing the present disclosure. Those skilled in the art willunderstand that the units in the device in the example may be arrangedin the device in the examples as described, or may be alternativelylocated in one or more devices different from that in the examples. Theunits in the examples described may be combined into one module orfurther divided into a plurality of sub-units.

Although the flowcharts described show a specific order of execution,the order of execution may differ from that which is depicted. Forexample, the order of execution of two or more blocks may be changedrelative to the order shown. Also, two or more blocks shown insuccession may be executed concurrently or with partial concurrence. Allsuch variations are within the scope of the present disclosure.

Throughout the present disclosure, the word “comprise”, or variationssuch as “comprises” or “comprising”, will be understood to imply theinclusion of a stated element, integer or step, or group of elements,integers or steps, but not the exclusion of any other element, integeror step, or group of elements, integers or steps. It will be appreciatedby persons skilled in the art that numerous variations and/ormodifications may be made to the above-described embodiments, withoutdeparting from the broad general scope of the present disclosure. Thepresent embodiments are, therefore, to be considered in all respects asillustrative and not restrictive.

1. A method for reconstructing a Computer Tomography (CT) imagecomprises: obtaining a X-ray projection data frame and a dynamic sensorinformation data frame, wherein the X-ray projection data frame has afirst timestamp indicating acquisition time of X-ray projection data andthe dynamic sensor information data frame has a second timestampindicating acquisition time of dynamic sensor information data;extracting the first timestamp from the X-ray projection data frame andextracting the second timestamp from the dynamic sensor information dataframe; searching X-ray projection data and dynamic sensor informationdata which are acquired in the same sampling period according to thefirst timestamp and the second timestamp; and reconstructing a CT imageaccording to the searched X-ray projection data and dynamic sensorinformation data which are acquired in the same sampling period.
 2. Themethod according to claim 1, wherein, the X-ray projection data of aX-ray projection data frame is acquired in a sampling period, and thedynamic sensor information data of a dynamic sensor information dataframe is acquired in a pre-determined time period, wherein thepre-determined time period is less than or equal to the sampling period.3. The method according to claim 1, wherein obtaining the X-rayprojection data frame comprises: acquiring X-ray projection dataaccording to a sampling period signal and recording acquisition time ofthe X-ray projection data; and generating a X-ray projection data frameaccording to the X-ray projection data acquired in the same samplingperiod and corresponding acquisition time, wherein the acquisition timeis recorded into a timestamp field of the X-ray projection data frame asthe first timestamp.
 4. The method according to claim 3, whereinrecording the acquisition time of the X-ray projection data comprises:recording the acquisition time of the X-ray projection data by a firstcounter of which value is incremented with 1 in a fixed time period,wherein the fixed time period is less than the sampling period.
 5. Themethod according to claim 1, wherein obtaining the dynamic sensorinformation data frame comprises: acquiring dynamic sensor informationdata and recording acquisition time of the dynamic sensor informationdata; and generating a dynamic sensor information data frame accordingto the dynamic sensor information data acquired in the samepre-determined time period and corresponding acquisition time, whereinthe acquisition time is recorded into a timestamp field of the dynamicsensor information data frame as the second timestamp.
 6. The methodaccording to claim 5, wherein recording the acquisition time of thedynamic sensor information data comprises: recording the acquisitiontime of the dynamic sensor information data by a second counter of whichvalue is incremented with 1 in a fixed time period, wherein the fixedtime period is less than the sampling period.
 7. An apparatus forcomputer tomography (CT) image reconstruction, comprising a processor,by reading and executing machine readable instructions of control logicfor reconstructing a CT image stored in a storage medium, the processoris caused to: obtain a X-ray projection data frame and a dynamic sensorinformation data frame, wherein the X-ray projection data frame has afirst timestamp indicating acquisition time of X-ray projection data andthe dynamic sensor information data frame has a second timestampindicating acquisition time of dynamic sensor information data; extractthe first timestamp from the X-ray projection data frame and extract thesecond timestamp from the dynamic sensor information data frame; searchX-ray projection data and dynamic sensor information data which areacquired in the same sampling period according to the first timestampand the second timestamp; and reconstruct a CT image according to thesearched X-ray projection data and dynamic sensor information data whichare acquired in the same sampling period.
 8. The apparatus according toclaim 7, wherein the X-ray projection data of a X-ray projection dataframe is acquired in a sampling period, and the dynamic sensorinformation data of a dynamic sensor information data frame is acquiredin a pre-determined time period, wherein the pre-determined time periodis less than or equal to the sampling period.
 9. The apparatus accordingto claim 7, wherein the machine readable instructions are further tocause the CPU to: acquire X-ray projection data according to a samplingperiod signal and recording acquisition time of the X-ray projectiondata; and generate a X-ray projection data frame according to the X-rayprojection data acquired in the same sampling period and correspondingacquisition time, wherein the acquisition time is recorded into atimestamp field of the X-ray projection data frame as the firsttimestamp.
 10. The apparatus according to claim 9, wherein the machinereadable instructions are further to cause the CPU to: record theacquisition time of the X-ray projection data by a first counter ofwhich value is incremented with 1 in a fixed time period, wherein thefixed time period is less than the sampling period.
 11. The apparatusaccording to claim 7, wherein the machine readable instructions arefurther to cause the CPU to: acquire dynamic sensor information data andrecording acquisition time of the dynamic sensor information data; andgenerate a dynamic sensor information data frame according to thedynamic sensor information data acquired in the same pre-determined timeperiod and corresponding acquisition time, wherein the acquisition timeis recorded into a timestamp field of the dynamic sensor informationdata frame as the second timestamp.
 12. The apparatus according to claim11, wherein the machine readable instructions are further to cause theCPU to: record the acquisition time of the dynamic sensor informationdata by a second counter of which value is incremented with 1 in a fixedtime period, wherein the fixed time period is less than the samplingperiod.